[grogenaut]

I worked on a AAA game. I controlled the networking code (web services really) down and the entire server infra for our project. All of that was full TDD but it was also all greenfield by me who had done heavy TDD before and working with an external team who was all TDD. I even wrote integration tests from a stub client that ran on the playstation as part of the build to hit my server and a stub server to do wire testing for the client as part of my builds. Also had a full load regression test as part of my build that ran every checkin on a smaller slower cluster.

The main game had no tests... except that you need to realize that we had 480GB of asset compiler integration tests and 32GB of game engine integration tests.

As a heavy TDD person it took me a long time to realize that this can be very sufficient though it's a longer turn around loop. The test coverage just from being able to boot the game up is quite large. This is something that many non-game type programs have real issues with, they can't easily just "run all the user data". I know we had one project where we did a lot of TDD but it wasn't actually as good as just running the entire input set every build which I eventually switched us to. This was a non-game data processing system. Doing this + unit testing gave us great coverage and few bugs.

Generally major bugs were found within 15 minutes by another engineer, eg the next person to sync, build or run the engine or art compiler.

I do think we could have unit tested the core collections libraries in the engine to great effect and faster turn around but the build was not really segregated in a way that we would take advantage of this. It was just a monolithic build; the collections objects were heavily header included so there really would have been a build step to built them into their own test exe, run them then build the game. So I'm not sure how much benefit we would have gotten. I think in 4 years I saw one collections issue that lasted past just launching the engine and not having it crash.